Greenhouse gas emissions levels are "considerably higher" than what will be needed to keep the global average temperature increase below 2 degrees Celsius, making it increasingly likely that the world will have to rely on costlier technologies like carbon capture and sequestration in order to meet the threshold in the coming decades, the "Emissions Gap Report 2013," says.

Moreover, five governments—Australia, China, the European Union, India and Russia—are on track to meet their carbon-cutting pledges. The United States, it says, is among four nations that will require "further action" or the purchase of carbon offsets in order to meet its emissions goals.

"The window of opportunity of trying to meet this 2-degree target threshold is, in a sense, becoming ever more elusive," UNEP Executive Director Achim Steiner said today, unveiling the report by webcast from Nairobi, Kenya.

"You can sit back for more years in your armchair and say, 'I don't want to do it,'" Steiner said. But, he said, "The window of opportunity, from a pragmatic and realistic point of view ... will make it more and more difficult to achieve the kinds of reduction targets we are looking for."

The annual study of the gap between the level of emissions that nations have pledged to cut and what scientists say is needed to avert an ice-free Arctic and dangerous levels of sea-level rise estimates that if countries stay on their current course, emissions will rise to 59 gigatons of carbon dioxide equivalent by 2020. The prediction is about 1 gigaton greater than last year's estimate.

If every country fully carries out its most stringent pledge, that would reduce emissions by 3 to 7 gigatons annually. Still, the authors found, that still leaves a gap of 8 to 12 gigatons over the 44-gigaton limit.

Delays will be expensive
Joseph Alcamo, UNEP's chief scientist, who oversaw the report, noted that without nations' emissions pledges, the gap would be as big as 15 gigatons. But as it is, the 12-gigaton gap is equivalent to 80 percent of all the greenhouse gas emissions from all the power plants in the world.

Next week, diplomats from around the world will meet in Warsaw, Poland, for an annual round of climate change negotiations. Nations have vowed to create a new global agreement by 2015 that will take effect in 2020. But vulnerable countries are expected to press the United States, Europe and other big emitters to do more in the short term, and analysts said the newest U.N. findings underscore the importance of acting soon.

Bridging the gap is still technically possible and can be done for about $50 to $100 per metric ton of CO2 equivalent, the authors found. Doing so demands more stringent accounting practices for emissions pledges, as well as ratcheting up those numbers. But, they warned, "time is running out."

"Although the emission reduction potential in 2020 remains high, time is running out with respect to realizing this potential," the authors wrote. "Failure to invest today in best available technologies and options not only represents a lost opportunity to reduce emissions, it also curtails our ability to reduce them in the near future as high energy use and emission patterns are locked in for several decades.

"Postponing action implies that part of the potential in 2020 may be lost and that steeper and more costly action will be required to achieve the remaining potential," they said.

For the first time, the study also has moved from just modeling out what would happen if the 13 countries accounting for 72 percent of global emissions met their pledges to studying what those countries are actually doing.

Further action needed from U.S.
The United States, which pledged to cut carbon about 17 percent below 2005 levels by the decade's end, will "require further action and/or offsets," the report found, adding that new action under President Obama's Climate Action Plan announced in June "may reduce projected 2020 emissions."

Canada, Japan and Mexico also will need to take more actions, it found, while a number of other countries, like Brazil, Indonesia and South Africa, could not be effectively examined because of "serious information gaps" including differences in the definitions and accounting of national emissions and the absence of independent and consistent databases.

Kelly Levin, a senior associate at the World Resources Institute and one of the authors of the report, said that stronger accounting rules will be key.

"This shows that we need for the next set of commitments a process to review country proposals with much more transparency," Levin said. "Part of the problem is that there is a lot of uncertainty."

Alcamo said that if countries tighten their pledges—making them unconditional rather than conditional on what other nations do—the world could reduce the gap by 4 gigatons. And if those cuts also broaden to include other greenhouse gases, like hydrofluorocarbons (HFCs) and methane, that would close another 2 gigatons, effectively halving the gap.

The other half, he said, will require more action from more countries.

Monica Araya, a member of UNEP's scientific steering committee and a former climate negotiator from Costa Rica, said middle-income and developing countries need to step up and start "saying no" to "high-emissions infrastructure that is being put in place in the name of development, often without much public debate."

Said Araya, "Unless we link this discussion on climate action to local political debates, the emissions gap will continue increasing."

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